On Jun 6, 2011, at 12:09 PM, J. Ryan Earl wrote:
> Hello,
>
> So I have a question about changing dfs.block.size in
> $HADOOP_HOME/conf/hdfs-site.xml. I understand that when files are created,
> blocksizes can be modified from default. What happens if you modify the
> blocksize of an existing HDFS site? Do newly created files get the default
> blocksize and old files remain the same?
Yes.
> Is there a way to change the
> blocksize of existing files; I'm assuming you could write MapReduce job to
> do it, but any build in facilities?
You can use distcp to copy the files back onto the same fs in a new
location. The new files should be in the new block size. Now you can move the
new files where the old files used to live.
